Introduction: Sponge Etching Method for PC-Board

Picture of Sponge Etching Method for PC-Board

When it comes to PCB etching, one of the most commonly used options to remove copper is Ferric Chloride (FeCl3) solution. Most of the methods described rely on submerging the copper clad board into a good quantity of etchant solution. To accelerate the process you are prompted to heat the solution and continuously agitate the bath. Although effective, this will take a rather long time to complete the process.

Alternately, the "Sponge Method" (with FeCl3) is amazingly fast (you can actually see the progress) and requires a very small quantity of etchant.

As with all FeCl3 etching methods, this must be carried out in a well ventilated space.

Step 1: The Sponge Method

Picture of The Sponge Method

The sponge method consists in wiping the copper clad board with a sponge saturated with FeCl3 solution. Any soft sponge will do. For small single sided boards I use a sponge designed for applying shoe polish which has a convenient plastic handle. For double sided boards, hold the board in your hand with protective gloves.

Step 2: Watch the Video for a Real-time Etching Demonstration

Step 3: How to Do It

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For single sided boards, stick inside a saucer or low profile container with a loop of masking tape

Step 4: Pour a Very Small Quantity of FeCl3

Picture of Pour a Very Small Quantity of FeCl3

Just enough etchant to cover the board.

Step 5: Etching

Picture of Etching

Gently wipe the board in all directions. In less than 2 minutes, your board is finished! .

Step 6: Final Step

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Remove the board, and rinse in water to stop the etching process.

I made this PCB with the Heatless Toner Transfer method:

Step 7: Thanks for Watching !


Razanur (author)2017-01-25

This sounds really amazing. In my university they were using a (I guess several thousand $$ [ ]) heat-spray-machine to do it - really amazing results. Thus I was testing to use a spray bottle at home - but it is rather hard/expensive to find acid resistant ones :D Also gives good results, but is of course rather messy and you still need large amounts of acid. This on the other hand is just clean, fast, beautiful! Thank you!

kcraske (author)2017-01-22

I agree this is a much faster method than just dunking boards in ferric chloride. I would say always use protective gloves irrespective of single or double sided boards and certainly no where near any thing of any value. Ferric chloride seems to magically get everywhere.
One thing that puzzles me. You say chlorine is given off. I did not think this was the case. It smells but I did not think it was chlorine nor can I see that in the reaction. Perhaps I'm wrong.

simpletronic made it! (author)kcraske2017-01-22

Chemistry is not my strong suit, but I found this on the net, and it could indicate Chlorine gas is released during the etching process.

simpletronic (author)kcraske2017-01-22

I had read somewhere and had always assumed chlorine was the responsible for the smell. Now after reading your comment and researching, i am in doubt. In any case, to avoid possible misinforming I have removed the statement from the article. Thank you! .

About This Instructable




Bio: Music: my profession for over 40 years... Electronics: my beloved hobby always.
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